The Sudanese government and southern rebels have extended a cease-fire until the end of June. But analysts say residual fighting is still continuing.

The three-month extension of last year's cease-fire deal is designed to boost the chances of a successful outcome at the ongoing peace talks between the Sudanese government and rebels of the Sudan People's Liberation Army.

The talks are being held in the Kenyan capital, Nairobi.

Chief Kenyan negotiator Lazaro Sumbeiywo has expressed confidence that a comprehensive peace deal will be signed later this year, bringing an end to 20 years of civil war in Africa's largest country.

But there are concerns that the cease-fire is not being respected as the two sides continue to fight for control of Sudan's oilfields.

"It is very encouraging that they have extended the cease-fire because at least it demonstrates that at the very top level there is going to be an emphasis on reduced conflict in Sudan," explained John Prendergast, Africa Program Director for the International Crisis Group, a Brussels-based research and analysis group. "But this unholy trinity of the oil companies, the government forces and these militias; this alliance will continue to pursue military objectives in terms of clearing space for oil field development as long as the international community does not raise too big a stink about it."

The Civilian Protection Monitoring Team, an international mechanism established to investigate attacks against civilians, found that the Sudanese government and allied militias are continuing to attack the oilfields of Western Upper Nile Province in an effort to dislodge the SPLA and expand oil industry development.

In February, the government and the rebels agreed to expand that monitoring team to investigate all cease-fire violations, not just attacks on civilians.

Mr. Prendergast of the International Crisis Group wants to see the re-enforced monitoring team on the ground in Sudan as soon as possible. "If we are serious about this peace process one of the most important things is ensuring that the parties live up to the interim agreements that they make along the way to demonstrate that, in fact, the larger agreement will stick and that the international community will support it and be behind it 100 percent. So it is imperative that a much higher number of monitors be hired and just get people on the ground and start looking at some of these violations and calling people on them whenever they do violate the agreement," he said.

The rebels took up arms against the Sudanese government in 1983 to fight for greater autonomy for the south. About two million people have so far died in the civil war, mostly through war-related famine.